I added skin to the body mesh and rigged the body mesh with biped bones. I didn't spend much time adjusting the weights as I knew I could use Edit Polygon to adjust them again. Next I opened Auto Key, and made the pose that you can see is Fig.04.

Fig.04

When finishing the pose, I converted the model to an editable poly and made adjustments such as changing the position and thickness of the arms, the length of the waist (the waist is long in the original painting), the position of the breasts and so on (Fig.05).

Fig.05

Sculpt

Next I exported that model into ZBrush and began to sculpt. There were no particular skills I used here; I just kept adjusting the image (Fig.06 - 07).